1. Field of the Invention
The present invention is a robotic actuator system that controls orientation, and, in particular, control methods for a robot wrist for supporting and orienting packages in the field of package shipping.
2. Statement of Related Art
In the field of package shipping, packages need to be stacked one on top of another in shipping containers and trucks for transporting between locations. These packages must also be removed one at a time from the those stacks when destinations are reached. These packages, which vary in size and weight, must be stacked and unstacked quickly and safely. Theoretically, mechanical robots may perform these stacking and unstacking functions.
Conventional anthropomorphic robots contain robot "arms," "wrists," and "hands" that perform, respectively, the functions of positioning, orienting, and gripping associated with human arms, wrists, and hands. In controlling a robot system, a controller must be provided to convert the positions of packages in a stack, or the desired location of packages in a stack, in a first coordinate system, to the location of motors in the robot arm and robot wrist, in a second coordinate system. In conventional robot systems, robot wrists are open-loop mechanical systems that provide orientation capability through a wide range of angular displacements. As open-loop systems, these robot wrists have kinematic linearity that permits straightforward closed-form solutions to problems of robot control. Such straightforward solutions are relatively capable of being achieved in real time.
Conventional open-loop wrists cannot handle the large payloads required during package handling in the field of package shipping. As a result, conventional open-loop robot wrists are not suitable for stacking and unstacking packages in the field of package shipping.
It is accordingly an object of the invention to provide a small and light robot wrist that can handle large payloads quickly, safely, and accurately, and be controlled using real-time processing.
It is a further object of this invention to provide a method of controlling a closed-loop robot wrist in real time.
Additional objects and advantages of the invention will become apparent from the detailed description of a preferred embodiment which follows.